In finite element modeling applied to structural analysis, the object under analysis is idealized as a collection of small elements interconnected at the nodal grids. There are two basic element classes, structural elements and mass elements. Structural elements, for example beam elements, have both stiffness (strength) and mass properties. Mass elements, for example lumped masses, have mass properties only. It is convenient to divide an object into structural and non-structural components for purposes of modeling its behavior. Structural components are modeled by structural elements, and non-structural components are modeled by mass elements. For example, in modeling an airplane fuselage, the structural component would typically comprise the fuselage, the beams, skin and floor, and the non-structural component would typically comprise the cargo, seats, passengers, contents of overhead bins, et cetera.
In many traditional finite element modeling methods, the non-structural components of the object are modeled by connecting lumped masses to the structure through rigid bars. The rigid bars offset the center of mass so that the lumped mass location corresponds to the center of mass of the object being modeled. This process may be labor intensive, difficult, costly, timely, inefficient, inaccurate, and/or may experience divergence during solution phase.
A finite element modeling method is needed which may solve one or more problems in one or more of the existing finite element modeling methods.